The invention relates to a firework accommodating apparatus, a firework and a method for launching a firework.
In all effects which come to fruition high in the night sky, it cannot be determined in which direction the stars are ejected. This is left to chance because spherical and cylindrical firework shells rotate about all three axes during the ascent and at the same time can also tumble vigorously and rockets can rotate about the longitudinal axis. The term rolling is used for a rotation about the longitudinal axis.
Since the invention of the firework, pyrotechnicians have made great efforts to make signs, symbols or letters appear in the night sky. So far however, this problem has not been satisfactorily solved.
Spherical and cylindrical shells with signs, symbols or letters have been known for a long time. This kind of shells is called pattern shells. If, for example the firework stars are placed in a heart shape into the burst charge during manufacture of the effect, it is entirely possible to achieve the effect that the stars are also dispersed in a heart shape in the sky. However, the spatial orientation cannot be determined because these firework shells rotate about all three axes during the ascent and in some cases tumble vigorously. As a result of the friction in the mortar during the launching and due to the air resistance in the ascent phase, the spherical and cylindrical shells are frequently set in violent rotation. It is left to chance in which spatial orientation the heart shape is formed. In rare and favourable cases it can be the case that the heart is displayed correctly for the observer at a specific location. Far more frequently however it happens that the heart is upside down for example or that all the firework stars lie one behind the other on one plane and instead of a broad heart shape, only a line can be identified. Typically numerous heart shells must be launched in order to be able to clearly identify a beautiful heart shape from time to time. This constitutes a very high expenditure, and the hearts which appear deformed can reduce the experiential value of a firework. With this technique it is inconceivable to produce letters and whole words in the sky.
In order to improve this problem, hitherto specific obvious measures have been taken to restrict the two undesired degrees of freedom of the rotation. Usually these are purely aerodynamic measures.
One possibility is to use firework rockets instead of spherical and cylindrical shells. Here for example we encounter the so-called shell rockets which can contain the required effect composition with the necessary burst charge. Naturally the rocket only rotates about its longitudinal axis during the ascent. For the example of the heart-shaped arrangement of the firework stars, in each case for example vertical hearts are produced which can be seen either randomly correctly in their full width or with a substantially smaller width or only as a perpendicular line for the spectators who are located at a certain location. Firework rockets in the professional display fireworks field usually have the disadvantage that a very large safety distance is required. In addition, a very large and powerful rocket motor must be used in order to be able to sufficiently accelerate sufficiently large, usually spherical rocket heads. The usually high speed of the rocket ascent in particular at the end of the thrust phase results in the undesired side effect that the effect images are frequently highly distorted.
Another possibility is to attach cables, chains and panels of fabric with or without weights and braking bodies to the spherical and cylindrical shells in order to restrict the degrees of freedom. This is sometimes used with the traditional Maltese firework in order to reduce the undesired rotation and tumbling during the flight path of pattern shells and to optimize the effect image so that the figures tend to be vertical and therefore can be identified correctly in the sky. Here also however there is the problem that the effect cannot always be seen in its full width. Frequently it can only be seen compressed, mirrored and in some cases only as a vertical line for the spectators at a certain location.
It is known from U.S. Pat. No. 5,339,741 (Disney, date of patent: 23 Aug. 1994, filing date: 7 Jan. 1992) that firework shells in the form of a projectile as is used in firearms have better flight properties compared with spherical and cylindrical shells and as a result the precision can be increased. Further described therein is an electronic delay fuse with exact time delay for professional display firework effects in order to increase the precision.
Known from U.S. Pat. No. 6,324,981 (Lacroix, priority: FR/98/01261, 23 Dec. 1998) is a firework with which it is possible to obtain figures, letters or any other signs in the sky. This is made possible according to the prior art whereby the sign is already stored in the firework with which it is to be written in the sky. In this invention the combustible material is in particular formed from a metal powder such as titanium having a granule size greater than 500 μm. The advantage of the metal powder is a particularly homogeneous and durable effect image in the night sky. In addition, aerodynamic measures were taken in this invention: firstly, a projectile-shaped geometry was selected instead of the spherical or cylindrical shape as was already state of the art at this time, and a type of skirt is added by means of a hollow cylindrical continuation with longitudinal slots. Both measures are intended to stabilize the flight path and restrict two degrees of freedom. A problem with this type of firework is that here also it is not ensured that the sign which is to be displayed in the sky can also be perceived as such by the spectators of the firework. Again it is left to chance in which angular position the burst charge ignites and whether the sign can be seen clearly. If a letter such as the horizontally implemented “S” depicted in the patent specification is to be shown, it can certainly occur that this is shown turned through 90° and the spectators at a certain location would rather identify a serpentine line and other letters which do not show the S would for example be turned upside down. If the sign is implemented vertically, it can also be perceived for the spectators as mirrored or having a compressed width or only as a vertical line.